I pulled the rear diff. cover today to change the fluid. It was low and turned to black sludge. Don't ask when the change was... let's just say it was way over due. 120k on the rig. Here's a photo with the cover off. I'm concerned about the passenger side drive shaft. It appears to be further into the pumpkin than the driver's side and very close to the pinion shaft. I have no experience with diffs. I also have been getting a whine coming from there (or at least I think it's from the rear diff.) whenever I'm on the gas. When coasting the whine is gone. Any thoughts? http://i801.photobucket.com/albums/y...pse8dc037f.jpg

YJ John

02-07-2013 09:33 PM

Re: Rear diff gears

off the subject... but to your 255/70 17's fit without spacers on factory wheels ? I would jack both sides up and pull the right side axle out, that looks like normal play to me. Compare movement right and left, my guess is just the way you parked before removed the cover had both as far to the left as possible.

wmassWK

02-07-2013 09:39 PM

Re: Rear diff gears

I'll give that a shot tomorrow thanks. The 255/70s do fit without spacers on stock rims but i do get rubbing on the drivers side frame rail at full lock

hummer recovery team

02-07-2013 11:07 PM

Re: Rear diff gears

I would think its normal play as well, the whine your getting could be a wheel bearing I had mine to out and took it to a driveline shop and they said diff was in great condition, make sure you clean the diff real good and use a high quality oil like royal purple or Mobil 1 75w140 gear oil and you will be set, also depending on the previous maintenance you should do the transfer case and front diff and tranny.

JHutch2012

02-09-2013 12:24 AM

Re: Rear diff gears

I too have that slight whine when on the gas. I had my tranny, transfer case, front and rear diffs serviced and there is no change in the noise. I cant figure it out either.

2005JGC

02-09-2013 03:59 PM

Re: Rear diff gears

the axle shafts float in the hub and side gears... Totally normal.

wmassWK

02-09-2013 06:36 PM

Re: Rear diff gears

Thanks for the info gentlemen. Dealing with snow now so tomorrow I'll swap the fluid in the front diff. and xfer case. The wheel bearings seem fine. May have the pinion and u joints checked this week for the humming. It's definitely driveline related.

4.whoa

02-12-2013 11:05 AM

Re: Rear diff gears

IIRC noise one way - on OR off throttle - has to do with ring & pinion mesh. maybe the pinion nut loosened or the preload was done wrong.

dmsfun

02-12-2013 11:17 AM

Re: Rear diff gears

Whine is probably the carrier bearing gone bad. Mine did the same, had bearing replaced and all good now.